Telephone-exchange apparatus



(No Model.)

1?. G. BEACH.

TELEPHONE EXCHANGE APPARATUS.-

Patented 0011.21, 1890.

UNITED STATES PATENT OFFICE,

FRANKLIN G. BEACH, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE AMERICAN BELL TELEPHONE COMPANY, OF BOSTON, MASSACHUSETTS.

TELEPHONE-EXCHANGE APPARATUS.

SPECIFICATION forming part of Letters Patent No. 438,982, dated October 21, 1890.

' Application filed February 5, 1889- Serial No. 298,747- (No model.)

To all whom it may concern.-

Be it known that I, FRANKLIN G. BEAoH, a citizen of the United States, residing at Chi cago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Telephone-Exchange Apparatus, (Case 7,) of which the following is a full, clear, concise, and exact description, reference being had to the accompanying draw- IO ing, forming a part of this specification.

In one system of telephoneexchange as heretofore used it has been common to provide individual telephone-lines for the different subscribers and a signal-oircuit common I5 to several subscribers, the listening operator at the central office being provided with a telephone included in the signal-circuit. The subscribers apparatus has been so arranged that any subscriber on taking down his telephone might speak directly over the signalcircuit to the listening operator. This sys tem has been known as the Firman or Law system. In other systems, however, which have been more largely and generally used the signals have been sent over the individual telephone-lines, an individual annunciator being included in each telephoneline at the central office, no special signalcircuit being required. Each of these sys- 3o tems possesses its own peculiar advantages and defects. It is sometimes desirable to com bine certain features of these two systems in the same exchange, and with this end in view I have provided telephone-line circuits adapted to be used either upon the plan of individual-annunciator calls or upon the plan of speaking directly to a listening operator.

This system, as hereinafter described, is especially designed for use in exchanges in which metallic circuits are employed. I have,

however, made provision for its use in exchanges having metallic-circuit lines and grounded lines connected with the same switch-board-that is to say,in mixed systerns, as those systems are sometimes termedhaving metallic telephone-lines and grounded telephone lines connected with the same switch-board.

My invention consists, first, in metallic-circuit telephone-lines in which one side or limb of each is grounded at the subscribers station thereon and connected through a signal-receiving device and switch at the subscribers station to a normally-open connection of the switch of the line upon the switch-board at 5 the central office, the other branch of each circuit being normally open at the subscribers station and extending through the switch and an individual annunciator at the central office to a common line in combination with two ground branches at the central office, one containing a battery or generator and the other thelistening operatorstelephoneandaswitching device in the common line for connecting the same, as desired, either to the branch containing the battery or to the branch containing thelistening operators telephone; second,

in pairs of loop plugs and cords, with a galvanometer and battery bridged between the cords to serve as a clearing-out signal; third, in a branch to ground containing an annunciator and a switch for connecting said branch to one of the strands of the pair of connecting-cords when used in connecting grounded lines with one another or with metallic-circuit lines; fourth, in a common line to which one side of each of several metallic circuits is connected, and a switch and a listening operators telephone, with which said common line is adapted to be connected by the switch and switching apparatus at the different subscribers stations of said telephone-lines arranged to permit any subscriber to connect his telephone into the side of his metallic circuit, which connects with the listening operators telephone; fifth, in metallic circuits, each having one side grounded at the subscribers station thereon and the other side normally open, said metallic circuit-s extending each to a switch on the switch-board, the 0 side of each which is grounded at its subscribers station being normally open at its switch-board switch and the other side passing through said switch and an individual annunciator to a common line, a switch for con- 5 meeting said common line with the battery at the will of the operator, and switches or keys at each of the subscribers stations, whereby any subscriber on closing his proper key or switch may bring the bell at his station and mo his individual annunciator at the central office into a circuit closed through said battery, and, sixth, in certain details of construction and combinations of circuits hereinafter described and claimed.

My invention will be more readily understood by reference to the accompanying drawing, which is a diagram showing two metalliccircuit lines and one grounded-circuit line connected with a central station, together with the central-station apparatus.

It will be understood that the grounded telephone-line a extends from ground at its subscribers station through a switch I) upon the switch-board and its individual annunciator c to ground in the usual manner. The insulated frame or tube, in multiple systems called the test portion, of switch bis provided with a ground-connection, as has been usual in some cases heretofore. The subscribers outfit upon line a consists of the usual telephonetransmitter and magneto-generator. Metallic circuit (1 consists of the two sides or limbs d (1 The subscribers apparatus of a metallic circuit is illustrated in detail at the subscribers station S of line d.

When the telephone is hung upon the hook, as shown, limb 01' will be connected through the bell e to ground at station S and will be open at the switch f of the line at the central office, said limb cl being connected with the insulated frame or ring of switch f. The other limb (1 will be open at the telephoneswitch of station S, and its circuit may be traced from the open contact g through the secondary of the induction-coil and the telephone to the spring of switch f, and thence through the contact of said switch, and thence through the individual annunciator h, and thence to the common line i. This line 2' is connected either with the branch 75, containing the battery l, or with the branch m, containing the operators telephone, by the switch n. Thus the branch 01 when the telephone is on the switch is open at S and closed at the central office, in some cases to a branch 70, containing battery, and in some cases to branch m, containing the operators telephone.

The subscriber at S by closing key 0 connects branch (I through bell e to ground, in this manner completing the circuit of said branch d through the ann unciator h and battery Z, provided branch is connected with common wire 1'. Thus the subscriber may throw down his individual annunciator 7b, the hell 6 responding, at the same time indicating to the subscriber that the battery Z is in circuit. Suppose, however, that the switch a is in position to close branch on to common wire t'. In this case subscriber at S, on taking down the telephone and depressing key 1), may speak directly to the operator listening at telephone in branch m. The circuit thus closed would be from ground at S through key 12, thence to contact g, thence over branch (Z through switch f and annunciator h to common wire 1', and thence to branch m, including the operators telephone.

I have found that in the day-time it is desirable in moderate-sized exchanges to have an operator at the central office with her telephone constantly in circuit, so that she will be ready to receive any communication from any subscriber which may require service. At night, however, I prefer to depend upon the individual-annunciator-call system, the annunciators being arranged in a well-known way to close a local circuit when operated,in which local circuit is included an alarm-bell. Therefore in actual practice I have the telephone branch 012 connected with the common wire 2' during the day and the battery branch 70 connected with said wire 1' at night. Either of the two systems-that is, the listening-operator system or the individual-annunciator system-may be used in connection with the same telephone-circuits.

I have shown a pair of loop-plugs q q connected with a pair of cords, the strand (1 of the cords being connected with the tips of the plugs, while the strand (1 is connected with the sleeves of said plugs. I have shown a generator with usual call-keys in the (litterent strands so arranged that current from the generator may be sent at will to the tip or sleeve of either of the plugs. The bridge 0" across the strands g (1 should be of high resistance-say three hundred ohms. In this bridge I have included a battery and a galvan ometer, designed as a clearing-out signal when the plugs are used to loop together two metallic circuits.

When grounded lines are used in the same exchange with metallic circuits, I provide a switch 7 and a branch r containing a clearing-out annunciator so arranged that the annunciator may be connected to the strand (1 when grounded lines are connected or when a metallic circuit is connected with a grounded line. I also provide a connection 4' with the operators telephone, so arranged that the operator may connect her telephone with strand r by means of switch 0" or by other suitable apparatus. It will be understood that the apparatus at station S is the same as hereinbefore described at S. The circuit .9 consists of two sides orbranches s sibranch 8 being connected with the insulated portion of switch 25 and branch 5 being connected through switch If and individual annunciator t to common wire i. If the exchange is too large for one operator, the lines will be arranged in groups, so that each operator will have only as many lines as she can conveniently attend to. If the exchange is so large that one board will not be large enough to give room for the operators required to do the work, I use multiple switch-boards.

The adaptation of my system herein to multiple switch-boards being so well understood, I have not deemed it necessary to make any detailed description of ihe manner of such adaptation.

It will be understood that the operator will IIO have as many pairs of plugs and cords as may be required, and that the particular forms of switching apparatus herein shown'may be varied without departing from my invention.

Suppose S takes down his telephone, at the same time grounding branch wire (1 He may then speak directly to the operator listening at the telephone in branch m, provided lineiis connected with said branch. He thus gives his order, we will say, for S The operator thereupon inserts one of the plugs q or q in switch t and, closing the generator to strand g in the proper direction, calls up S The other plug of the pair being inserted in switch f, the two subscribers will be looped together in metallic circuit as soon as S has taken down his telephone. The galvanometer included in bridge 0" will then be deflected and remain deflected until both subscribers hang up their telephones.

The insertion of the plugs in switches f t cuts off the annunciators h and t. The subsoriber of the grounded line a in order to call turns the magnetogenerator, sending current through annunciator c in the usual manner. The operator, observing the signal, inserts a plug of a pair, as plug q, in switch I), bringing switch '1' into connection with telephone-connection r and is ready to re ceive the order. The order being received, we will say, for connection with line d, she inserts plug q in switch f of line at, and, depressing calling-key t throws the generator onto branch d, thus ringing belle. The subscribers being connected, she moves switch 0'' from telephone-connection r to clearing-out annunciator connection or branch 1*. The subscribers lines a and d are then connected together. The circuit thus formed would be traced from ground at subscribers station of line a to spring of switch I), thence to tip of plug q, thence through strand g to tip of plug q, thence to spring of switch f, thence over limb d through station S and back over limb d to sleeve of switch q, and thence over strand g to sleeve of plug q, said sleeve being in contact with the insulated piece of switch I), which is grounded, and the circuit would be complete. The disconnecting-signal would be sent by the subscriber of line a, who is provided with the magneto-generator. Two single lines could be connected together in substantially the same manner.

It is obvious that either portion of my invention would be a complete system in itselfthat is to say, the branch is, containing the battery Z, together with the individual annunciators ht, might be dispensed with-and the system would be operative, the line 'i being connected with the branch 122. On the other hand, the means forconnecting the operators telephone with line t' might be dispensed with, and the system would be operative according to the individual-annunciator plan; but, as hereinbefore stated, I prefer to combine the two systems in the same apparatus in order that the individual-annunciafor the operator to connect her telephone into the circuit of two subscribers when connected together in metallic circuit. The conversation may thus be carried on secretly between the subscribers. When both hang up their telephones, the clearing-out signal will be indicated by the pointer of the galvanometer in the bridge returning to zero. It is obvious, however, that provision might be made for bridging the operators telephone between the strands in place of the galvanometer so that the operator might listen in. If desired, the clearing-out annunciator might be placed in a bridge-wire instead of the branch wire 0. The switch 7 may be in the form of a listening-key adapted to be operated most conveniently to bring the required instrument into connection with the talking-circuit, whether metallic or grounded.

I have sometimes placed an annunciator in the branch wire is, thus dispensing with the individual annunciators h t of the metallic circuits. In such case the night operator, seeing the shutter in wire 70 fall, would immediately switch over to branch m, and the subscriber, taking down his; telephone and depressing his appropriate key, as key 19, would give his order.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. The combination, with two telephonelines looped together in metallic circuit, of a galvanometer and battery in a bridge including resistance bridged across the strands of the cords by which the lines are connected at the central office, whereby said galvanometer is deflected while the circuit remains complete, the pointer of the galvanometer returning to zero when the subscribers hang up their telephones.

2. The combination, with a pair of loop plugs of double-stranded cords, with which strands the different terminals of the loopplugs are respectively connected, of a bridge across the strands including a battery and an electric indicating device, a switch in said bridge, and a branch to ground including an annunciator, with which branch the switch is adapted to be connected to open the bridge and form an electrical connection with one of the strands through the annunciator to ground, substantially as and for the purpose specified.

3. An operators telephone connected with a common line branched through different switches on a switch-board and each branch extending to a different subscribers station and being there normally open, said branches each forming one limb of the metallic circuit of the station to which it is extended, the other branch of which circuit being normally grounded at its subscribers station and ex- IIO tending to the insulated portion of the switch of its line upon the switch-board at the central office, a subscribers outfit at each station, consisting of a bell, telephone, and telephone-switch, together with a circuit-closing device for connecting the telephone-switch directly to ground when the telephone is re moved from the hook to bring the telephone into circuit, a pair of loop-plugs and doublestranded flexible cords with which the plugs are connected, and a high-resistance bridge, including a galvanometer and battery, connecting the two strands, whereby any subscriber may speak directly over one branch of his telephone-line to the listening operator, 15 and whereby the operator may loop any two lines together, while upon the subscribers hanging up their telephones the clearing-out signal will be indicated.

In witness whereof I hereunto subscribe 20 my name this 24th day of January, A. D. 1889.

FRANKLIN G. BEACH.

Vitnesses:

ELLA EDLER, GEORGE P. BARTON. 

